Electrochemical sensors are analytical devices comprising a biological diagnosis element and a suitable convertor. The convertor converts chemical change resulting from an interaction between molecules and a receptor into an output signal. The receptor agent can be an enzyme, a microorganism, a tissue or an antibody, a nucleic acid or a bio-ligand that can be a synthetic detector. The main application areas are quality control procedures in agriculture food and pharmaceutics industry, biological war agents causing environmental pollution and medical diagnosis methods. Diagnosis applications are bio-indicators available in the human body fluids, such as metabolites, proteins or nucleic acids which are related to a disease. The concentration of a bio-indicator in the body fluids is used to determine the type, condition or progress of a disease as well as the response of the patient to the treatment. In the market, there are a great variety of electrochemical sensors such as blood sugar, cholesterol, uric acid and lactic acid biosensors. Blood sugar biosensors used by the diabetic patients are the most common biosensors.
Electrochemical biosensors mainly comprise a working electrode modified with biological identification agent, a reference electrode and a counter electrode. Typically, electrodes are placed on a planar surface with a tool used for carrying fluid sample/reaction agents. Electrochemical sensors comprise a batch electrode (working, reference or counter) for measuring an analyte (sample) or an electrode series for multiple analyte measurements. Typical measurement technique is a flow sensitive measurement technique, which is performed by measuring a voltage generated by an enzyme, due to a biochemical reaction, using an electrochemical device.
Measurement of analytes with an electrochemical sensor array requires a tool for carrying the fluid into the sensor array for analysis purposes. To this end, in order to carry the fluid within the sensor array, an apparatus can be designed that is capable of establishing a proper connection with the electrodes and that can be mounted to and released from the device in an easy manner. For disposable sensors, such apparatus should not be expensive and should be easily manufactured. The flow cell provided in the apparatus must be small so that a lower amount of sample is used, and must allow a uniform distribution of fluid to all electrodes. In order to increase diffuse of analytes around the electrodes and to reduce mass transfer effects, it is preferred that the distance between the electrodes and the upper wall of the flow cell is small.
International patent document WO2008/154416, as part of the state-of-art, describes electrochemical biosensors and arrays. The inventive device comprises a structural body or layer. The body comprises a lower or bottom layer, an intermediate layer or a binding layer and an upper layer. Inside the body, there is a reservoir. The device also comprises a working electrode, a reference electrode and an auxiliary electrode. The working electrode and reference electrode are located in the reservoir whereas the auxiliary electrode is located outside the reservoir. A cover for reservoir surrounds the opening inside the reservoir. The device also comprises a sensor chemical inside the reservoir. The sensor chemical may be an enzyme or one or more polymer layers.
In international patent document WO2008/127269 the apparatus comprises a support body comprising a receiving surface and a receiving substrate. The support body comprises a mesa located within a recessed area. The fluid cell structure has a silicone or similar elastomer compressible layer around the mesa. The depth of the recessed area less the height of the mesa is the height of the interior volume of the fluidic cell once the plastic support body and planar substrate are secured together. This height is carefully measured to achieve the appropriate fluidic cell height to optimize fluid flow versus mass transfer conditions for the intended biochemical assay application. Fluidic inlet and outlet ports are drilled in the mesa for the attachment of external tubing.
US2008/0182136 describes an electrochemical cell with a micro scale and method for incorporating the cell. An electrochemical cell for processing a sample fluid has a body with a flow path. The flow path comprises an inlet and an outlet. The cell also comprises a reference electrode, a counter electrode in fluid communication with the flow path and a working electrode in fluid communication with the flow path. In an embodiment of the document, the invention comprises a body having a cell fluid manifold. The manifold has a primary flow path through which a sample fluid passes. The flow path has an inlet and an outlet, and is in fluid communication with at least two secondary conduits.